Primary squamous cell carcinoma of breast presenting as a cystic massCS Sheela1, P Ramakant2, G Shah3, V Chandramohan4, D Abraham2, MJ Paul2
1 Department of General Surgery, Christian Medical College, Vellore, Tamil Nadu, India
2 Department of Endocrine and Breast Surgery, Christian Medical College, Vellore, Tamil Nadu, India
3 Department of Pathology, Christian Medical College, Vellore, Tamil Nadu, India
4 Department of Radiology, Christian Medical College, Vellore, Tamil Nadu, India
Correspondence Address: Source of Support: None, Conflict of Interest: None DOI: 10.4103/0022-3859.113839
Source of Support: None, Conflict of Interest: None
Pure squamous cell carcinoma (SCC) is a rare pathological subtype, comprising of 0.1% of all breast cancers. 
A 54-year-old postmenopausal lady presented with a 2 month history of right breast lump following blunt trauma. The lump was increasing in size and was painful. On examination, the breast was enlarged with a 10 cm × 8 cm warm, mildly tender, well-defined cystic mass extending from 12 o' clock to the 3 o' clock position. It had displaced the nipple, but was not fixed to the overlying skin/chest wall. There were no palpable lymph nodes. In view of the history of trauma and presence of a cystic lump a clinical diagnosis of traumatic fat necrosis was made.
Mammography showed a predominantly fat replaced breast with a large 10.4 × 9.7 cm circumscribed high density mass on the inner aspect of the right breast with obscured margins. There was mild skin thickening. There were no associated microcalcifications, nipple retraction or axillary nodes. An ultrasound showed a thick walled complex cystic lesion with mobile echogenic debris and posterior acoustic enhancement.
Approximately 200 ml of thick, dark blood was aspirated collapsing the lesion, suggesting an infected hematoma. She was managed conservatively, but the swelling completely returned on Day 7 review raising the suspicion of malignancy. After a failed core biopsy attempt, she underwent an excision biopsy. Histopathological examination of the specimen showed pure SCC of the breast. On gross examination, there was a cystic mass of 9.5 cm diameter. The luminal surface was ragged with central pale soft material representing keratin.
Microscopically, breast tissue infiltrated by a cystic tumor composed of well differentiated squamous cells arranged in diffuse sheets and few anastomosing thin trabecule, extending into deep stroma. Individual cell keratinization and occasional keratin pearls were present [Figure 1]. Immunostaining was positive for cytokeratin 5/6 and negative for estrogen, progesterone and Human Epidermal Growth Factor Receptor 2 (Her 2)/neu.
She underwent a completion modified radical mastectomy and is currently undergoing adjuvant chemotherapy and radiation therapy.
Pure primary SCC of the breast are those that are comprised entirely of malignant squamous cells, have no relation with the overlying skin and are not associated with a primary elsewhere. 
Metaplastic breast cancers usually lack characteristic malignant features, are cystic masses with complex echogenicity on ultrasonography and commonly show posterior acoustic enhancement. Cystic appearance is due to extensive hemorrhage and necrosis within the tumor. 
In contrast to SCCs elsewhere, SCC of the breast shows lower incidence of lymph node metastasis, around 10%. , Axillary dissection may be carried out in only clinically/on image suspicious lymphadenopathy. Our patient presented with a large tumor, but histopathological examination did not reveal positive nodes.
Staging and management are along the guidelines of other invasive cancers of the breast. Mostly these are hormone receptor negative and so not amenable to hormone therapy. Radio sensitivity of these cancers is also uncertain. ,
Squamous cell cancers of the breast generally carry a poorer prognosis than other pathological subtypes. In a study of 11 patients over 30 years, 5 year survival rate was found to be 67%. 
SCC may have varied presentations like a cystic mass or abscess. In postmenopausal women, SCC of breast may mimic a breast abscess. , SCC breast usually do not respond to anthracycline/taxane based chemotherapy, however, they have been found to be responsive to platinum based chemotherapy. 
SCC is a rare malignancy of the breast. An elderly woman with a cystic mass must raise suspicion of this entity. Lower rates of lymph node metastasis, more frequent systemic metastasis and a poorer prognosis are some differentiating characteristics.